Pneumatic gyroscope with porous pickup



' Dec. 23, 1969 H- L. GERWIN 3,485,106

PNEUMATIC GYROSCOPE WITH POROUS PTCKUP Filed June 28, 1968 United StatesPatent 3,485,106 PNEUMATIC GYROSCOPE WITH POROUS PICKUP Harry L. Gerwin,Silver Spring, Md., assignor to the United States of America asrepresented by the Secretary of the Army Filed June 28, 1968, Ser. No.740,956 Int. Cl. G01c 19/28 US. Cl. 745.6 7 Claims ABSTRACT OF THEDISCLOSURE A closed container having an air inlet and a gyroscopemounted within the container. The inner gimbal of the gyroscope carriesa dome-shaped member having a central nozzle opening therethrough. Aporous open cellular element is carried by the container and has asurface conforming to and in slightly spaced registry from thedome-shaped member. Air collection chambers are equally spaced about theporous member and have air pickotf passages. An air leak gland isprovided about the porous element. Air flowing into the container flowsthrough the nozzle into the porous element where it is trans mitted tothe collection chambers in proportion to the angular position of thenozzle relative to predetermined axis of the porous element.

The present invention relates to an attitude sensor and particularly toa gyroscope having a pneumatic pickoff wherein deviations in attitudefrom a predetermined attitude are sensed and translated to pneumaticsignals.

Directional control systems in the past have provided complex apparatusfor guiding movable bodies along predetermined courses. These apparatussuffer various disadvantages such as relatively high bulk and weight,and space limitations, as well as those factors previously mentioned,are critical in the provision of an attitude sensor.

The present invention provides a gyroscopic directional control systemhaving pneumatic pickoif signals for sensing the attitude deviation of abody from a predetermined attitude and which invention minimizes theabovediscussed and other shortcomings of prior directional controlsystems employed for like purposes and provides various advantages inconstruction, mode of operation and result over such prior systems. Toaccomplish this, the present directional control system provides agyroscope carried within a closed fluid tight container. The containerhas an air inlet connected with an air supply under pressure and aporous open-cellular element forming a portion of the wall of thecontainer. The inner gimbal of the gyroscope carries a dome-shapedelement having a central passage therethrough forming a nozzle. Theinner surface of the porous element is concavely spherical to conformwith the dome-shaped element. The gyroscope and porous element arelocated such that the nozzle containing the dome-shaped element lies inslightly spaced registry from the conforming spherical surface of theporous element such that the air flowing into the container flowsthrough the nozzle into the porous element. Air collection chambers arearranged at predetermined spaced positions about the porous elementwhereby the air issuing through the nozzle and into the porous elementis transmitted into the collection chambers for ultimate communicationwith pneumatic amplifiers connected to an attitude control. Thus, thechambers collect the fluid transmitted through the porous element inproportion to the angular position of the nozzle relative to the elementand hence in proportion to the change "ice in attitude of the bodymounting the container relative to the gyroscope.

It is a further feature of the present invention that spurious air flowbetween the dome-shaped member and the porous element is eliminated. Tothis end, an air leak gland is provided about the porous element suchthat air in the container flows through the air leak gland withoutentering the area between the porous element and domeshaped member inthe area of the nozzle. The air issuing through the nozzle thusconstitutes the sole air input to the porous element and spuriouspneumatic signals are eliminated.

Accordingly, it is a primary object of the present invention to providean improved directional control device.

It is another object of the present invention to provide a directionalcontrol system including a gyroscope with a pneumatic pickotf.

It is still another object of the present invention to provide adirectional control system including a gyroscope with a pneumaticpickoff.

It is still another object of the persent invention to provide adirectional control including a gyroscope with a porous element wherebyattitude deviations from a predetermined attitude are sensed bypneumatic signals transmitted through the porous element.

It is a further object of the present invention to provide an attitudecontrol device which is economical to manufacture, simple and efficientin operation, and has excellent sensitivity characteristics.

These and further objects and advantages of the present invention willbecome more apparent upon reference to the following specification,claims and appended drawings, wherein:

FIGURE 1 is a cross-sectional view of an attitude sensor constructed inaccordance with the present invention;

FIGURE 2 is a horizontal cross-sectional view thereof taken about online 22 of FIGURE 1; and

FIGURE 3 is a horizontal cross-sectional view thereof taken about online 3-3 of FIGURE 1.

Referring now to FIGURE 1, there is shown an attitude sensor generallyindicated at 10 comprising a cylindrical, fluid-tight container 12having circular upper and lower end walls 14 and 16, respectively, andmounting a gyroscope generally indicated at 18. Container 12 has an airinlet conduit 20 which connects to a suitable pneumatic source, notshown, and a circular aperture 22 through upper wall 14 for purposes aswill presently become clear.

Gyroscope 18 comprises an outer gimbal 24 pivotally mounted to container12 in any suitable manner as at 26 and an inner gimbal 28 pivotallymounted to outer gimbal 24 as at 30 such that the pivotal axes of thegimbals lie at right angles to one another. Inner gimbal 28 carries apair of spaced cross support members 32 which pivotally mount a rotor orrotating mass 34 as at 36. Suitable means, not shown, are provided forrotating rotor 34. It is thus seen that gyro 18 is a free gyro, that is,gyro 18 is not constrained to follow the motions of container 12. Itwill be understood that the present invention may also be employed witha single axis gyro and that the free gyro disclosed is for illustrativepurposes only as the present invention is not limited thereto.

A spherical or dome-shaped member 38 is carried on inner gimbal 28 bymeans of four upstanding posts 40 which are suitably connected at theirlower ends to the upper support 32 of gimbal 28 and connected at theirupper ends to the concave underside of member 38. The wall portions 42about opening 22 conform in shape to the outer convex surface ofspherical member 38. Member 38 is slightly spaced from conforming wallportions 42 to provide an annular air leak passage 43 for continuouslytransmitting air out of container 12 for purposes as will presentlybecome clear. A central aperture or nozzle 44 is formed through member38 and this, together with the annular air leak passage 43, form thesole fluid outlets from container 12.

An inverted, cup-shaped container 46 is suitably secured to container 12in sealing relation about opening 22. Container 46 suitably supports acylindrical porous element 48 from its upper end. Porous element 48 ispreferably formed of a homogenous open cellular mate rial such as anopen celled plastic foam or a porous sintered metal. The lower surface50 of element 48 conforms in shape to the outer surface of member 38,i.e., surface 50 is concavely spherical. Cylindrical element 48 isinwardly spaced from the sidewalls of container 46 as to provide anannular area 52 thereabout. Four fluid outlets 54 are equally spacedabout container 46 in fluid communication with annular area 52. Annulararea 52 is preferably divided into four quadrants by baflles 56, asshown in FIGURE 3, whereby the annular portions between the bafflescomprise quandrantal collection chambers 57 communicating withassociated fluid outlets 54. The lower spherically concave surface 50 ofelement 48 is slightly spaced from the outer convex surface of member38.

In use, air flows continuously into container 12 via inlet conduit 20and flows out of container 12 into the quadrantal collection chambers 57and associated outlets 54 by way of the annular air leak passage 43 orthe nozzle 44. It will be appreciated that the air flowing into thequadrantal collection chambers via the air leak passage 43 providesequal air flow into the fluid outlets 54 as the annular passage 43 issymmetrical about the collection quadrants. When the gyro axis,coincident with rotor axis 36, is coincident with the central verticalaxis of element 48, it will be seen that air flowing through nozzle 44will be equally dispersed throughout porous element 48 such that lateralair flow from element 48 into the quadrantal collection chambersprovides equal air flow through the outlet conduits 54. Should thecontainer 12 be inclined relative to gyro 18, it will be seen that thenozzle 44 will be offset from the vertical axis of element 48. When thisoccurs, the air flowing through nozzle 44 will be dispersed throughoutporous element 48 with a larger proportion of the air flowing into oneor more of the quadrantal collection chambers 57 which lie closer tonozzle 44. Thus, the air flow out of the associated fluid outlets 54will be greater than the air flow through the other conduits 54communicating with the collection chambers further spaced from nozzle44. This change in attitude of the container 12 relative to the gyro isthus sensed and the increased air flow through the one or more outletconduits 54 can be fed through pneumatic amplifiers, not shown, toprovide the desired corrective or stabilizing action of the body, notshown, housing the gyro to which container 12 would be rigidly attached.Y

It is a significant feature hereof that spurious air flow between thespherical member 38 and the lower surface 50 of porous element 48 whichmight provide an erroneous pneumatic signal if transmit-ted throughelement 48, is entirely eliminated. By providing the annular air leakpassage 43 between member 38 and the wall portions 42 of container 12,whereby the continuously flowing air is evenly distributed into thequadrantal collection chambers, air flow between element 48 and member38 in the area of surface 50 and nozzle 44, other than that air issuingfrom nozzle 44, is eliminated. Thus, the air issuing through nozzle 44constitutes the sole air input to porous element 48.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive.

What is claimed and desired to be secured by United States LettersPatent is:

1. An attitude sensing device comprising a support, a gyroscope havingat least one gimbal mounting a rotor and carried by said support, anozzle carried by said gimbal for discharging fluid under pressure, afluid transmitting element carried by said support in registry oppositesaid nozzle for receiving the pressure fluid issuing therefrom, saidelement being formed of a porous material and having a surface areaagainst which the pressure fluid from said nozzle is directed largerthan the exit area of said nozzle, fluid collection passages located atpredetermined positions about and in communication with said porouselement and adapted to receive fluid transmitted through said element inproportion to the angular position of the nozzle relative to thesupport.

2. A sensing device according to claim 1 including a dome-shaped membercarried by said gimbal, said nozzle comprising a passage through saidmember, a surface area of said element being concavely spherical andconforming to and in slightly spaced registry with the convex face ofthe dome-shaped member.

3. A sensing device according to claim 2 wherein said support structurecomprises a closed container, said container having a fluid pressureinlet, said element comprising a fluid outlet from said container, thepressure fluid in said container issuing through the passage in saiddome-shaped member and through said element into said collectionpassages.

4. A sensing device according to claim 3 wherein said element is carriedby a wall of said container, an air leak opening about said elementthrough said wall and in slightly spaced relation about said member, thepressure fluid in the container flowing through said opening into saidcollection passages.

5. A sensing device according to claim 1 wherein said passages includefluid collection chambers equally spaced about said element.

6. A sensing device according to claim 1 wherein said element is formedof a sintered metal.

7. A sensing device according to claim 1 wherein said element is formedof an open cellular plastic material.

References Cited UNITED STATES PATENTS 1,932,412 10/1933 Keen. 2,315,1673/1943 Manteuffel et al. 74-5.6 XR 2,539,363 1/1951 Dawson 74-5.72,960,873 11/1960 Lundberg 745.6 XR 3,339,420 9/1967 Paine 74-5.7 XR3,416,378 12/1968 Evans et al. 745.6

FRED C. MATTERN, JR., Primary Examiner MANUEL A. ANTONAKAS, AssistantExaminer

